The 'It bag' you never considered

A girl always needs a bag – otherwise, where would she keep her wallet, keys, iPad and the million other random items she needs every day? But sometimes, she also needs her hands. Cross-body bags are usually too small (and can cut her body in an unflattering way), and larger messenger bags, while functional, sit awkwardly on the hip (like any of us need that).

What's a girl to do? Go old school – literally. Remember what you carried in school?

A backpack!

It's my humble, and often scoffed-at, opinion that the backpack could be the next "It Bag" – the bag silhouette everyone will be carrying for the next two years.

Don't believe me? Ask the Olsen twins.

Mary-Kate and Ashley – darlings in the fashion world for their impeccable taste and otherworldly dedication to bespoke tailoring and high-quality textiles in their couture line The Row – include a version of the backpack in their new collection for Elizabeth and James, their ready-to-wear line. The bag is available in calf hair for $445 at niemanmarcus.com or in luscious lambskin (pictured here) at French e-tailer mode-b.com for $590. But the Olsens are such big fans of the backpack that they already made news with The Row version that can cost up to – not kidding – $39,000 if you get it in alligator. The drawstring satchel is as luxurious as a backpack has ever dreamed of being, but it's not the priciest the pair has turned out; recently, Lady Gaga gave her boyfriend a limited edition $55,000 version designed by artist Damien Hirst for The Row.

These days, there are backpack styles – and price points – for every woman, whether she's City Sleek, an Urban Warrior or a Beachy Babe.

City Sleek: You like minimal, luxe design with enough room to carry your wallet, phone and a small makeup bag but not so big that you look like you're going on an expedition. For you: a smaller backpack with classic hardware and ladylike style.

Urban Warrior: Going through your day requires a bag with the same kind of tough-girl style you ooze. Not just basic black, but black leather with spikes and studs; a 24/7 "go bag" that holds everything from your DJ-worthy headphones to a change of clothes, because who knows when you'll make it home again?

Beachy Babe: On any given day you may get a chance to hit the waves and grab some rays, so you pack a bag that holds your bikini, beach towel and sunscreen in style. Bright stripes and rainbow colors in a sturdy wear-everywhere pack suit you just fine.